1. Field of the Invention
The invention disclosed herein is directed to methods for the design of epitope-encoding vectors, and epitope cluster regions, for use in compositions, including for example, pharmaceutical compositions capable of inducing an immune response in a subject to whom the compositions are administered. The invention is further directed to the vectors themselves. The epitope(s) expressed using such vectors can stimulate a cellular immune response against a target cell displaying the epitope(s).
2. Description of the Related Art
The immune system can be categorized into two discrete effector arms. The first is innate immunity, which involves numerous cellular components and soluble factors that respond to all infectious challenges. The other is the adaptive immune response, which is customized to respond specifically to precise epitopes from infectious agents. The adaptive immune response is further broken down into two effector arms known as the humoral and cellular immune systems. The humoral arm is centered on the production of antibodies by B-lymphocytes while the cellular arm involves the killer cell activity of cytotoxic T Lymphocytes.
Cytotoxic T Lymphocytes (CTL) do not recognize epitopes on the infectious agents themselves. Rather, CTL detect fragments of antigens derived from infectious agents that are displayed on the surface of infected cells. As a result antigens are visible to CTL only after they have been processed by the infected cell and thus displayed on the surface of the cell.
The antigen processing and display system on the surface of cells has been well established. CTL recognize short peptide antigens, which are displayed on the surface in non-covalent association with class I major histocompatibility complex molecules (MHC). These class I peptides are in turn derived from the degradation of cytosolic proteins.